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## Measurement & Data - Statistics & Probability 176-188

# Time on a number line

Sal tells time on a number line. Created by Sal Khan.

## Want to join the conversation?

- why do we need a number line?(10 votes)
- It tends to be easier for some people to understand simple counting with a number line.(15 votes)

- Isn’t A Timeline like when event’s happen?(Like for e.x. The timeline of Jackie Robinson )(8 votes)
- It's like a number line but on the tick marks are dates that show when important events happen.(6 votes)

- Why do we call the clock hands "hands" its weird!?(8 votes)
- why a number line wut is the point...!?(6 votes)
- Number lines can make it easier to visualize problems. You’ll use them a lot as you get older.(2 votes)

- Ya why is it called a numberline(5 votes)
- Because a number line is a line with numbers on it.(2 votes)

- do we need the number line?(2 votes)
- The number line is not necessary, but thinking of numbers as points on a line is often very helpful.(5 votes)

- what is a nickle(2 votes)
- A nickel is 5 cents in the USA.(5 votes)

- Can you marke 1 hour on the time line(3 votes)
- If you'd like to mark the actual time:
then yes, all you'd have to do is place the tick mark at the1:001:00. However, if you mean 1 hour as in the span of time, then you'd probably go over the timeline from1:00-2:00(because an hour has passed between1:00and2:00) with a line to signify that you're referring to an entire hour passing.

I hope I answered you're question :)

by the way, sorry that when I wrote things like "1:00" and "2:00" it underlined it. It probably thought I was referring to times in the video.(2 votes)

- why do we need a number line?(3 votes)
- Number lines can help us in figuring out negative and positive numbers. For example, if we want to know what -22 + 23 is, then we can draw a number line to see that the answer is 1.

I hope this helped!(2 votes)

## Video transcript

- [Instructor] We're told to look at the following number line. In this number line, we
actually have times on it, so you could even call it a timeline. We're starting at one o'clock here. Then we go to 1:15, 1:30,
1:45, then two o'clock. And it says, what time is
shown on the number line? So, pause this video and see
if you can figure that out. All right, so the hour I think
is pretty straightforward. We are past one o'clock but
we are before two o'clock. So, we know that the hour is
going to be one something. It's not going to be two something 'cause we haven't gotten
to two o'clock yet. Now, what is the number of
minutes after one o'clock? Well, we have a hint here. It's going to be between 15 and 30. And where would it be? Well, one way to tell is if you look at each of these tick marks, it looks like they represent a minute. Let's just count. If we start at one, we go to 1:01, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15. Yep, it looks like each of
these tick marks is a minute. So, we just have to figure out how many tick marks we are past 1:15. So, we can see that we
can go from 15 to 16, 17, 18, 19, 20, 21, 22, 23, 24, 25. So, we're 25 minutes past one o'clock. Another way you could
have thought about it is each of these medium tick
marks represent five minutes. And you can count, one,
two, three, four, five. So, that's five, that's another five. So, this time right over here is going to be five plus five is 10, it's going to be 10 minutes past 1:15. Well, 15 plus 10 is 25 again. So, the time shown on
the number line 1:25.